Embodiments presented herein relate generally to aerodynamic surfaces configured for wake desensitization, and more specifically to configuration of a leading edge on an aerodynamic surface, such as an airfoil, for desensitization of unsteady pressure response to impinging wakes and vortices from upstream.
At least some known machines including aerodynamic surfaces such as, but not limited to, aircraft engines, gas turbine engines, and steam turbine engines, include a plurality of rotating airfoils and stationary airfoils which are subject to impinging wakes and vortices generated from an upstream object, such as an upstream blade row, or an input unsteady airflow. The upstream generated wakes and vortices are channeled downstream where they may impinge on the leading edge of downstream airfoils. In several instances, the wake flow impingement from upstream objects on the downstream airfoils moving relative to each other is a dominant source of aerodynamic noise and aeromechanical loading generated in turbomachinery applications. In some known rotary machines noise may be generated by an upstream rotating airfoil's wake impinging on a leading edge of a stationary or rotating airfoil located downstream, an upstream stator component's wake impinging on a leading edge of a rotating or stationary airfoil located downstream, or an upstream rotating airfoil's wake impinging on a leading edge of a counter-rotating airfoil located downstream. In some known engines, the wake flow may contain non-uniform temperature distributions.
Noise generated by aircraft engines may be constrained by international and local regulations, thereby creating a need to balance fuel efficiency and emissions with noise pollution. A dominant source of aerodynamic noise and aeromechanical loading generated in turbomachinery applications is the interaction of wakes from upstream blade rows on downstream blade rows or vanes moving relative to each other. Examples include fan wakes interacting with downstream outlet guide vanes (OGVs), contra-rotating open rotor noise generated by forward-aft rotor interaction, booster noise from fan wakes impinging on booster inlet guide vanes (IGVs), or the like. More particularly, an impinging wake flow on an airfoil's leading edge may result in an increase in noise radiated from the turbomachinery, as well as a potential increase in aeromechanical loading on the blade row. Desensitization by decorrelation in time of the unsteady pressure response as well as a reduction in the amplitude of the wake flow may reduce the noise and the aeromechanical loading generated when the wake impinges on the leading edge of the blade row or vane. At least some known methods of reducing the amplitude of the wake flow on a downstream airfoil include increasing the distance between the upstream object or airfoil and the downstream airfoil. This increased distance mixes the wake flow and thus reduces the amplitude of the wake flow impinging on the leading edge of the airfoil. However, increasing the distance between an upstream object and the downstream airfoil may increase the size, weight, and cost of the engine, and thereby reduces the efficiency and performance of the engine.